The objective of the proposed study is to develop a subcutaneous implant of risperidone which provides consistent therapeutic blood levels of the drug for 3 months. The benefits of such product include improved medication adherence, the ability to withdraw the medication if needed due to treatment emergent Adverse Effects (AEs), fewer relapses, and improved efficacy. Atypical antipsychotics have been used for several years with great results for the treatment of schizophrenia. However, the effectiveness of these agents in maintenance treatment is limited due to patient non-adherence. Lack of medication adherence has been shown to highly correlate with relapse and re-hospitalization. With each successive relapse, the patient's long-term prognosis deteriorates and previous level of functioning is rarely achieved. Patient non-adherence also places an additional burden on the US healthcare system, which is estimated at $2.3 Billion per year. The proposed formulation of risperidone will be delivered through a small subcutaneous reservoir, which can be implanted during a simple, 15 minute, in office procedure. Although some subcutaneous implant technologies already exist, none of them is suitable for the delivery of risperidone or other antipsychotics. The results of recent studies show that 86% of healthcare providers and 50% of patients support the use of implants in this disease area. The proposed study will validate the technology employed and optimize the formulation and the implant design through a series of in-vitro and in-vivo tests. The same technology may also be used in the future for other antipsychotics or other classes of drugs that may benefit from such delivery. The clinical benefits of long acting antipsychotic formulations have already been proven with depot formulations. Relative to daily oral therapy, a two-week injectable depot formulation of risperidone is associated with improved treatment adherence, improvement in clinical symptoms, and greater reduction in hospital stays in patients with schizophrenia. However, two critical barriers have impeded the development of longer acting depot formulations: Safety issues since the drug cannot be withdrawn after administration, and technical limits of depot technology to provide consistent blood levels for more than 2-4 weeks. The current program is designed to address these problems and provide the following benefits over existing depots: Improved patient adherence (3 month release instead of 2 weeks); Ability to withdraw the medication if needed (not possible with depot formulations); Superior pharmacokinetic profile (no peaks and troughs resulting in better safety and efficacy); Reduced invasiveness (one procedure replaces 6 painful injections); Reduced cost (fewer relapses and doctor visits) PUBLIC HEALTH RELEVANCE: The proposed product will reduce relapses during maintenance treatment, improve safety, and increase overall treatment success, for patients suffering from schizophrenia. The final outcome will be an improvement in patient lives, and a reduction in overall healthcare costs.